As examples of an ophthalmic lens for correcting astigmatism, eyeglasses, contact lenses, intraocular lenses and the like are named. These ophthalmic lenses have an optical surface referred to as a toric surface. It is noted that “toric surface” is a surface shape of a lens where radii of curvature of at least two meridians differ from each other as in the case of a side surface of a rugby ball or a doughnut. Accordingly, a lens having such a toric surface is referred to as a toric lens (circular annular lens).
Due to a toric surface, the refractivity of a lens differs between directions orthogonal to each other which are set on the toric surface. Astigmatism can be corrected by making use of the difference in refractivity. In general, this difference in refractivity is referred to as cylindrical refractivity. On a toric surface, a meridian in a direction where refractivity is large is referred to as a steep meridian, and a meridian in a direction where refractivity is small is referred to as a flat meridian. Further, an average value of refractivities on these two meridians is referred to as spherical equivalent power (or simply referred to as spherical power). Usually, in an ophthalmic lens for correcting astigmatism, as indexes indicative of optical performances, equivalent spherical power and cylindrical refractivity are used. Conventionally, there has been proposed a lens where, with respect to optical surfaces disposed in front of and behind the lens, a function of correcting astigmatic abnormality in vision is imparted to one optical surface, and a function of correcting spherical aberration is imparted to the other optical surface (patent literature 1).